A method for stabilizing a lingual fixed retainer in place prior to bonding.

J Contemp Dent Pract. 2007;8(7):108-13

Authors: Al-Emran S, Barakati R

AIM: The objective of this article is to present a simple technique for stabilizing a lingual fixed retainer wire in place with good adaptation to the teeth surfaces and checking for occlusal interferences prior to the bonding procedure. BACKGROUND: Bonding of an upper or lower fixed lingual retainer using stainless steel wires of different sizes and shapes is a common orthodontic procedure. The retainer can be constructed in a dental laboratory, made at chair side, or it can be purchased in prefabricated form. All three ways of creating a fixed retainer are acceptable. However, the method of holding the retainer wire in place adjacent to the lingual surfaces of the teeth before proceeding with the bonding process remains a problem for some practitioners. REPORT: The lingual fixed retainer was fabricated using three pieces of .010" steel ligature wire which were twisted into a single strand wire. Another four to five 0.010" pieces of steel ligature wires were twisted in the same way to serve as an anchor wire from the labial side of the teeth. The retainer wire was bonded using the foible composite. SUMMARY: The technique presented here for stabilizing the retainer wire prior to bonding provides good stabilization, adaptation, and proper positioning of the retainer wire while eliminating contamination of etched surfaces which might arise during wire positioning before bonding. This technique also allows the clinician the opportunity to check the occlusion and adjust the retainer wire to avoid occlusal interference prior to bonding maxillary retainers. This same clinical strategy can be used to stabilize wires for splinting periodontally affected teeth and traumatized teeth.

PMID: 17994162 [PubMed - in process]

In vitro comparison of NiTi rotary instruments and stainless steel hand instruments in root canal preparations of primary and permanent molar.

J Indian Soc Pedod Prev Dent. 2006 Dec;24(4):186-91

Authors: Nagaratna PJ, Shashikiran ND, Subbareddy VV

This study is an attempt to compare the NiTi rotary and K-files hand instrumentation on root canal preparation of primary and permanent molars for their efficiency in preparation time, instrument failure and shaping the canals. About 20 primary mandibular second molar (I) and 20 permanent mandibular first molar (II) were selected. Each was further divided into 10 for K-files (a) and 10 for NiTi (b) groups, respectively. Results showed that preparation time Ib Ia and IIab<IIa, which was highly significant. In instrument failure, Ia (40%), IIa (30%) showed more deformation but not fracture and Ib (10%), IIb (20%) showed fracture, but not deformation. Profiles showed good canal taper and smoothness compared to the K-files. To conclude profile 0.04 taper 29 series, prepared canal rapidly than conventional K-file with good taper, smoothness though the flow was not satisfactory. Instrument failure with K-files was less. In primary teeth preparation time, instrument failure with profile was less compared to the permanent. To conclude it's encouraging to use the profiles in primary teeth.

PMID: 17183182 [PubMed - indexed for MEDLINE]

Fracture strength of custom-fabricated Celay all-ceramic post and core restored endodontically treated teeth.

Chin Med J (Engl). 2006 Nov 5;119(21):1815-20

Authors: Zhang YX, Zhang WH, Lu ZY, Wang KL

BACKGROUND: The increased use of all-ceramic crown provides a rationale for tooth-colored core. Due to superior mechanical properties, Vita Celay infiltration ceramic developed for crown and bridge works presents the potential for fabricating all-ceramic posts and cores in one piece. This study was conducted to compare the fracture strength of endodontically treated teeth which were thereafter given different types of posts and cores and crowns restoration, respectively. The evaluated post-and-core systems are: custom-fabricated Celay all-ceramic post-core, custom cast metal post-core, and prefabricated stainless steel post (Parapost) with and without 2.0 mm dentine ferrule. METHODS: Sixty freshly extracted human maxillary central incisors were endodontically treated and randomly divided into five groups with 12 samples each. Group A: Celay ceramic post-cores restored teeth with 2.0 mm dentine ferrule. Group B: Celay ceramic post-cores restored teeth with no dentine ferrule. Group C: cast metal post-cores restored teeth with 2.0 mm dentine ferrule. Group D: cast metal post-cores restored teeth with no dentine ferrule. Group E: prefabricated post and composite cores restored teeth with 2.0 mm dentine ferrule. All teeth were restored with Celay ceramic crowns. Each specimen was subjected to a load at a 45-degree angle to the long axis on MTS 810 material testing machine until failure, at crosshead speed of 0.02 cm/minute. Analysis of variance followed by the Newman-Keuls pairwise multiple comparison tests were used to compare the results of the groups tested. RESULTS: There was a statistically significant difference among the five groups (P < 0.01). Celay ceramic post-cores restored teeth with 2.0 mm dentine ferrule [(758.35+/-19.26) N] and cast metal post-cores restored teeth with 2.0 mm dentine ferrule [(756.63+/-66.22) N] had a significantly greater mean fracture strength than the other three groups in which no significant difference was observed. The 2.0 mm dentine ferrule could cause significant fracture resistance alteration of Celay post-core restored teeth. CONCLUSIONS: When covered with Celay ceramic crowns, Celay post-cores restored teeth with 2.0 mm dentine ferrule and cast metal post-cores restored teeth with 2.0 mm dentine ferrule have similar fracture strength. There was a statistically significant difference between the fracture resistance of Celay post-core restored teeth with and without 2.0 mm dentine ferrule.

PMID: 17097037 [PubMed - indexed for MEDLINE]

Which orthodontic archwire sequence? A randomized clinical trial.

Eur J Orthod. 2006 Dec;28(6):561-6

Authors: Mandall N, Lowe C, Worthington H, Sandler J, Derwent S, Abdi-Oskouei M, Ward S

The aim of this study was to compare three orthodontic archwire sequences. One hundred and fifty-four 10- to 17-year-old patients were treated in three centres and randomly allocated to one of three groups: A = 0.016-inch nickel titanium (NiTi), 0.018 x 0.025-inch NiTi, and 0.019 x 0.025-inch stainless steel (SS); B = 0.016-inch NiTi, 0.016-inch SS, 0.020-inch SS, and 0.019 x 0.025-inch SS; and C = 0.016 x 0.022-inch copper (Cu) NiTi, 0.019 x 0.025-inch CuNiTi, and 0.019 x 0.025-inch SS. At each archwire change and for each arch, the patients completed discomfort scores on a seven-point Likert scale at 4 hours, 24 hours, 3 days, and 1 week. Time in days and the number of visits taken to reach a 0.019 x 0.025-inch SS working archwires were calculated. A periapical radiograph of the upper left central incisor was taken at the start of the treatment and after placement of the 0.019 x 0.025-inch SS wire so root resorption could be assessed. There were no statistically significant differences between archwire sequences A, B, or C for patient discomfort (P > 0.05) or root resorption (P = 0.58). The number of visits required to reach the working archwire was greater for sequence B than for A (P = 0.012) but this could not be explained by the increased number of archwires used in sequence B.

PMID: 17041083 [PubMed - indexed for MEDLINE]

[Clinical study of Twin-wires on anchorage on canine retraction]

Shanghai Kou Qiang Yi Xue. 2006 Jun;15(3):332-4

Authors: Wang GH, Liu P, Ou YM

PURPOSE: The purpose of the study was to evaluate the effects of anchorage by Twin-wires on canine retraction. METHODS: A sample of 15 patients with severe anterior crowding was selected (6 males, 9 females, age average: 13.7 years). All patients underwent removal of the four first premolars during orthodontic treatment. Retraction of canine was achieved by using 0.018 stainless steel wire and NiTi wire. Anchorage reinforcement as a result of this movement was evaluated. The length and width of the dental arch models were measured. Self-control t test was used for data analysis. RESULTS: The length and width of the dental arches, the canine and molar relationships remained unchanged after orthodontic treatment. CONCLUSION: Application of Twin-wires leads to canine retraction and sufficient anchorage consolidation.

PMID: 16862375 [PubMed - in process]

Contraction stress in dentin adhesives bonded to dentin.

J Dent Res. 2006 Aug;85(8):728-32

Authors: Hashimoto M, de Gee AJ, Kaga M, Feilzer AJ

Adhesives cured under constrained conditions develop contraction stresses. We hypothesized that, with dentin as a bonding substrate, the stress would reach a maximum, followed by a continuous decline. Stress development was determined with a tensilometer for two total-etch systems and two systems with self-etching primers. The adhesives were placed in a thin layer between a glass plate and a flat dentin surface pretreated with phosphoric acid or self-etching primer. After an initial maximum shortly after light-curing, the stress decreased dramatically for the total-etch systems (70%) and, to a lesser extent, for the adhesives with self-etching primers (30%). The greater stress decrease for the total-etch systems was ascribed to water and/or solvents released into the adhesives from the fully opened dentinal tubules by the pulling/sucking action of the contraction stress. This happened less with the adhesives with self-etching primers, where the tubules remained mainly closed.

PMID: 16861290 [PubMed - indexed for MEDLINE]

NSK reciprocating handpiece: in vitro comparative analysis of dentinal removal during root canal preparation by different operators.

Braz Dent J. 2006;17(1):10-4

Authors: Wagner MH, Barletta FB, Reis Mde S, Mello LL, Ferreira R, Fernandes AL

The purpose of this study was to assess dentin removal during root canal preparation by different operators using a NSK reciprocating handpiece. Eighty-four human single-rooted mandibular premolars were hand instrumented using Triple-Flex stainless-steel files (Kerr) up to #30, weighed in analytical balance and randomly assigned to 4 groups (n=21). All specimens were mechanically prepared at the working length with #35 to #45 Triple-Flex files (Kerr) coupled to a NSK (TEP-E10R, Nakanishi Inc.) reciprocating handpiece powered by an electric motor (Endo Plus; VK Driller). Groups 1 to 4 were prepared by a professor of Endodontics, an endodontist, a third-year dental student and a general dentist, respectively. Teeth were reweighed after root canal preparation. The difference between weights was calculated and the means of dentin removal in each group were analyzed statistically by ANOVA and Tukey's test at 5 % significance level. The greatest amount of dentin removal was found in group 4, followed by groups 2, 3 and 1. Group 4 differed statistically from the other groups regarding dentin removal means [p<0.001 (group 1); p=0.005 (group 2); and p=0.001 (group 3)]. No statistically significant difference was found between groups 1 and 2 (p=0.608), 1 and 3 (p=0.914) and 2 and 3 (p=0.938). In conclusion, although the group prepared by a general dentist differed statistically from the other groups in terms of amount of dentin removal, this difference was clinically irrelevant. The NSK reciprocating handpiece powered by an electric engine was proved an effective auxiliary tool in root canal preparation, regardless of the operator's skills.

PMID: 16721457 [PubMed - indexed for MEDLINE]

Fixed space maintainers combined with open-face stainless steel crowns.

J Contemp Dent Pract. 2006 May 1;7(2):95-103

Authors: Yilmaz Y, Kocogullari ME, Belduz N

OBJECTIVE: This study investigates the clinical performance of fixed space maintainers placed on seriously damaged abutment teeth. METHODS: Crowns were placed on damaged abutment primary teeth. Fixed space maintainers were prepared by using rectangular wire between the window in the facial surface of the crowns and other abutment teeth and were subsequently bonded with a flowable resin composite. This procedure was introduced clinically, and the cases were observed over a period of twelve months. RESULTS: Twenty-seven fixed space maintainers (25 on lower jaw, two on upper jaw) were included in this study. No clinical failure was recorded in any of the cases in the observation time, and the rate of clinical performance was 100%. CONCLUSION: The study shows the effectiveness of fixed space maintainers combined with stainless steel crowns ("open-face fixed space maintainers") which were placed on primary molar teeth used as abutments in cases with extensive caries and loss of occlusogingival dimension.

PMID: 16685300 [PubMed - indexed for MEDLINE]

An investigation into the use of a single component self-etching primer adhesive system for orthodontic bonding: a randomized controlled clinical trial.

J Orthod. 2006 Mar;33(1):38-44; discussion 28

Authors: House K, Ireland AJ, Sherriff M

OBJECTIVE: This study assessed the in vivo bond failure of the single component orthodontic self-etching primer system, Ideal 1 (GAC Orthodontic Products) and compared it with the conventional acid etching using a conventional 37% o-phosphoric acid, rinsing and drying regimen when bonding stainless steel orthodontic brackets to enamel. DESIGN: Prospective randomized, controlled clinical trial. SETTING: Orthodontic Department, Bristol Dental School. MATERIAL AND METHODS: Twenty consecutive patients undergoing upper and lower fixed orthodontic treatment entered this cross-mouth control study. Diagonally opposite quadrants were randomly allocated to either the self-etching primer group or the conventional etching group. A total of 339 teeth were bonded with Ideal 1 light-cured adhesive. Bond failures and locus of bond failure were then recorded at 1, 6 and 12 months. RESULTS: Significantly more bond failures occurred at each of the 3 time intervals, 1, 6 and 12 months, where the enamel was pretreated with the Ideal I self-etching primer, than when the enamel was treated with the conventional etchant, 37% o-phosphoric acid. With the latter the cumulative bond failure rates were 3.0, 5.3 and 14.8%, respectively. With the self-etching primer the cumulative failure rates were 29.4, 56.5 and 72.4%. CONCLUSION: The study found that enamel pre-treatment with the Ideal 1 self-etching primer system prior to orthodontic bonding results in an unacceptably high bond failure rate when compared with conventional enamel acid etching.

PMID: 16514132 [PubMed - indexed for MEDLINE]

Inactivation of prions by acidic sodium dodecyl sulfate.

J Virol. 2006 Jan;80(1):322-31

Authors: Peretz D, Supattapone S, Giles K, Vergara J, Freyman Y, Lessard P, Safar JG, Glidden DV, McCulloch C, Nguyen HO, Scott M, Dearmond SJ, Prusiner SB

Prompted by the discovery that prions become protease-sensitive after exposure to branched polyamine dendrimers in acetic acid (AcOH) (S. Supattapone, H. Wille, L. Uyechi, J. Safar, P. Tremblay, F. C. Szoka, F. E. Cohen, S. B. Prusiner, and M. R. Scott, J. Virol. 75:3453-3461, 2001), we investigated the inactivation of prions by sodium dodecyl sulfate (SDS) in weak acid. As judged by sensitivity to proteolytic digestion, the disease-causing prion protein (PrPSc) was denatured at room temperature by SDS at pH values of < or =4.5 or > or =10. Exposure of Sc237 prions in Syrian hamster brain homogenates to 1% SDS and 0.5% AcOH at room temperature resulted in a reduction of prion titer by a factor of ca. 10(7); however, all of the bioassay hamsters eventually developed prion disease. When various concentrations of SDS and AcOH were tested, the duration and temperature of exposure acted synergistically to inactivate both hamster Sc237 prions and human sporadic Creutzfeldt-Jakob disease (sCJD) prions. The inactivation of prions in brain homogenates and those bound to stainless steel wires was evaluated by using bioassays in transgenic mice. sCJD prions were more than 100,000 times more resistant to inactivation than Sc237 prions, demonstrating that inactivation procedures validated on rodent prions cannot be extrapolated to inactivation of human prions. Some procedures that significantly reduced prion titers in brain homogenates had a limited effect on prions bound to the surface of stainless steel wires. Using acidic SDS combined with autoclaving for 15 min, human sCJD prions bound to stainless steel wires were eliminated. Our findings form the basis for a noncorrosive system that is suitable for inactivating prions on surgical instruments, as well as on other medical and dental equipment.

PMID: 16352557 [PubMed - indexed for MEDLINE]

Effectiveness of computerized delivery of intrasulcular anesthetic in primary molars.

J Am Dent Assoc. 2005 Oct;136(10):1418-25

Authors: Ashkenazi M, Blumer S, Eli I

BACKGROUND: Pain measures associated with computerized delivery of intrasulcular anesthestic have not been reported. The authors evaluated a computerized delivery system for intrasulcular (CDS-IS) anesthesia in primary molars. METHODS; The study population consisted of children aged 2 to 13 years who received CDS-IS injections, 159 in mandibular molars and 48 in maxillary molars. Children were treated by one of three modes of behavioral management: behavior modification (BM) only, inhalation of nitrous oxide (N2O) in addition to BM or intrarectal sedation. Variables evaluated included the subjective perception of the child's well-being before and after administration of the anesthetic, the child's pain behavior during anesthetic administration, effectiveness of the anesthetic during dental treatment, incidence of reported postoperative dental pain (PDP) and analgesic use after the CDS-IS injections. RESULTS: The effectiveness of CDS-IS anesthesia in mandibular molars was 97 percent, 92 percent, 63 percent and 71 percent for restorations, preformed stainless steel crowns, extractions and pulpal therapies, respectively (mean effectiveness, 89 percent). The effectiveness of CDS-IS anesthesia in maxillary molars was 96 percent, 50 percent, 92 percent and 78 percent, respectively (mean effectiveness, 90 percent). CDS-IS was less effective in children aged 2 to 4 years who received sedation than it was in older children. The authors found no differences between children's subjective self-reports of well-being before and after anesthetic administration, between the sexes and/or between modes of behavioral management (that is, BM or N2O). Most children exhibited low pain-related behavior during anesthetic administration, with no differences between boys and girls. The overall incidence of PDP was 31.4 percent; 64.9 percent of these patients received pain-relieving medications as a result, with no correlation to age, tooth treated, effectiveness of anesthesia or type of treatment. CONCLUSIONS: CDS-IS is effective for anesthetizing primary molars, mainly for amalgam, resin-based composite and stainless steel crown restorations.

PMID: 16255467 [PubMed - indexed for MEDLINE]

Ion release and cytotoxicity of stainless steel wires.

Eur J Orthod. 2005 Dec;27(6):533-40

Authors: Oh KT, Kim KN

Heat treatment is generally applied to orthodontic stainless steel (SS) wires to relieve the stresses that result from their manipulation by orthodontists. The quality and thickness of the oxide films formed on the surface of heat-treated wires can vary, and it is believed that these oxide films can influence the properties of heat-treated wires. The aim of this study was to investigate the influence of heat treatment and cooling methods on the amount of metal ions released and to examine the cytotoxicity of heat-treated wires. In this study, four types of SS wires (Remanium, Permachrome, Colboloy and Orthos) with a cross-sectional area of 0.41 x 0.56 mm were investigated. These wires were heat-treated in a vacuum, air, or argon environment, and were cooled in either a furnace or a water bath. Four control groups and 24 experimental groups were classified according to the type of wires, heat treatment conditions and cooling methods. In each group, the amount of nickel released as well as its cytotoxicity was investigated. The concentration of dissolved nickel ions in artificial saliva was measured for a period of up to 12 weeks. In all groups, the concentration of dissolved nickel ions in artificial saliva was lowest for the vacuum heat treatment-furnace cooling group and a significant difference was shown compared with the other experimental groups. The concentration of dissolved nickel ions in artificial saliva was highest in the groups heat-treated in air (P < 0.05), while the amount of nickel released was highest in the Remanium and Colboloy (P < 0.05). The cytotoxicity was mild in all the experimental groups but the response index of the air groups was slightly higher than in the other groups. According to these results, SS wires retain their high corrosion resistance and low ion release rate when heat-treated in a vacuum and cooled in a furnace.

PMID: 16093259 [PubMed - indexed for MEDLINE]

Tensile bond strength of brackets after antioxidant treatment on bleached teeth.

Eur J Orthod. 2005 Oct;27(5):466-71

Authors: Bulut H, Kaya AD, Turkun M

Various studies have reported a significant reduction in tensile bond strength of brackets when bonding is carried out immediately after bleaching. The purpose of this investigation was to determine the effect of an antioxidant agent on the tensile bond strength values of metal brackets bonded with composite resin to human enamel after bleaching with carbamide peroxide (CP). A total of 80 extracted premolar teeth were randomly divided into three bleaching groups of 10 per cent CP and an unbleached control group. The specimens in group 1 were bonded immediately after bleaching; group 2 were stored in an artificial saliva solution for 7 days after bleaching; group 3 were treated with 10 per cent sodium ascorbate, immediately before bonding, whereas the unbleached specimens in group 4 had no treatment before bonding. Tensile bond strengths were established in MPa. To evaluate the amount of resin left on the enamel surfaces after debonding, the adhesive remnant index (ARI) scores were used. The tensile bond strength data were analyzed with the Kruskal-Wallis test and pairwise comparisons were made by the Mann-Whitney U test at a significance level of P < 0.05. The brackets bonded immediately after bleaching revealed significantly lower tensile bond strengths than those of unbleached enamel (P = 0.000). No statistically significant differences in tensile bond strength were noted when the delayed-bonding (P = 6.000) and antioxidant-treated (P = 0.2757) groups were compared with the control group. The antioxidant treatment immediately after bleaching was effective in reversing the tensile bond strength of brackets.

PMID: 16043470 [PubMed - indexed for MEDLINE]

British Orthodontic Society, Chapman Prize Winner 2003. A novel in vitro culture model to investigate the reaction of the dentine-pulp complex to orthodontic force.

J Orthod. 2005 Jun;32(2):122-32

Authors: Dhopatkar AA, Sloan AJ, Rock WP, Cooper PR, Smith AJ

OBJECTIVE: To develop a novel mandible slice organ culture model to investigate the effects of externally applied force on the dentine-pulp complex. DESIGN: In vitro organ culture. SETTING: School of Dentistry, Birmingham, UK. MATERIALS AND METHODS: Transverse 2 mm thick sections were cut from the mandibles of five 28-day-old male Wistar rats. Serial sections were used for control and test pairs. Springs made from 0.016-inch and 0.019 x 0.025-inch stainless steel wires were used to apply a 50 g tensile or compressive force, respectively, to test specimens. Control and test specimens were cultured for 5 days in a humidified incubator with 5% CO(2) at 37 degrees C and processed for routine histological investigation. Nine more rats were used to provide control and compression test pairs where the pulps were extirpated after 3 days culture and total RNA isolated for gene expression analysis by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Histology showed the dental and supporting tissues maintained a healthy appearance in the control cultures after culture. Histomorphometric analysis revealed a 20-27% increase in pulp fibroblast density in test specimens compared with controls. Gene expression analyses revealed up-regulation in the test groups of PCNA, c-Myc, Collagen 1alpha, TGF-beta1 and alkaline phosphatase, whilst expression of osteocalcin was reduced. CONCLUSIONS: The results demonstrated that the present organ culture technique provides a valuable in vitro experimental model for studying the effects of externally applied forces. These forces stimulated a cellular response in the pulp chamber characterized by altered gene expression and proliferation of fibroblasts; the latter being unaffected by the nature of the force in terms of compression or tension.

PMID: 15994986 [PubMed - indexed for MEDLINE]

Light curing time reduction: in vitro evaluation of new intensive light-emitting diode curing units.

Eur J Orthod. 2005 Aug;27(4):408-12

Authors: Mavropoulos A, Staudt CB, Kiliaridis S, Krejci I

The aim of the present in vitro study was to establish the minimum necessary curing time to bond stainless steel brackets (Mini Diamond Twin) using new, intensive, light-emitting diode (LED) curing units. Seventy-five bovine primary incisors were divided into five equal groups. A standard light curing adhesive (Transbond XT) was used to bond the stainless steel brackets using different lamps and curing times. Two groups were bonded using an intensive LED curing lamp (Ortholux LED) for 5 and 10 seconds. Two more groups were bonded using another intensive LED curing device (Ultra-Lume LED 5) also for 5 and 10 seconds. Finally, a high-output halogen lamp (Optilux 501) was used for 40 seconds to bond the final group, which served as a positive control. All teeth were fixed in hard acrylic and stored for 24 hours in water at 37 degrees C. Shear bond strength (SBS) was measured using an Instron testing machine. Weibull distribution and analysis of variance were used to test for significant differences.The SBS values obtained were significantly different between groups (P < 0.001). When used for 10 seconds, the intensive LED curing units achieved sufficient SBS, comparable with the control. In contrast, 5 seconds resulted in significantly lower SBS. The adhesive remnant index (ARI) was not significantly affected.A curing time of 10 seconds was found to be sufficient to bond metallic brackets to incisors using intensive LED curing units. These new, comparatively inexpensive, curing lamps seem to be an advantageous alternative to conventional halogen lamps for bonding orthodontic brackets.

PMID: 15961571 [PubMed - indexed for MEDLINE]

An investigation into the use of two polyacid-modified composite resins (compomers) and a resin-modified glass poly(alkenoate) cement used to retain orthodontic bands.

Eur J Orthod. 2005 Jun;27(3):245-51

Authors: Williams PH, Sherriff M, Ireland AJ

The aim of this investigation was to determine the effectiveness of a conventional glass poly(alkenoate) cement (Intact) and newer polyacid-modified composite resin cements (Transbond Plus and Ultra Band-Lok) to retain orthodontic bands.In the in vitro part of this study, stainless steel bands were cemented to 240 extracted third molar teeth in three test groups comprising Intact, Transbond Plus and Ultra Band-Lok. The force to deband (N) for all three cements was recorded using an Instron universal testing machine after the following observation periods: 20 minutes and 3, 6 and 12 months. The results indicated that all three cements increased their median force to deband after 12 months. Of the two compomers, Transbondtrade mark Plus demonstrated the highest median force to deband at all four time intervals.In the in vivo part of the study, 30 patients participated in a randomized cross-mouth clinical trial where the molar bands were cemented in place using either Intact or Transbond Plus. Ultra Band-Lok was not used in the clinical part of the study. The results showed there to be no clinically significant difference in band failure rates between the two cements. When patients were asked to score each for taste, there was a significant difference, with the glass poly(alkenoate) cement (Intact) being more acceptable than the polyacid-modified composite Transbond Plus (P < 0.001).No significant differences were observed in the in vitro median force to deband or in vivo band failure rates between the glass poly(alkenoate) cement and the polyacid-modified composite resins. The choice of cementing agent can therefore be made on patient factors, e.g. taste, or operator factors, e.g. ease of handling, cost and shelf life.

PMID: 15947223 [PubMed - indexed for MEDLINE]

Office reconditioning of stainless steel orthodontic attachments.

Eur J Orthod. 2005 Jun;27(3):231-6

Authors: Quick AN, Harris AM, Joseph VP

An investigation was conducted to determine a simple, effective method for reconditioning stainless steel orthodontic attachments in the orthodontic office. In total, 100 new brackets were bonded to premolar teeth, then debonded and the bond strength recorded as a control for the reconditioning process. The debonded brackets were divided into six groups and each group reconditioned using different techniques as follows: attachments in four groups were flamed and then either (1) sandblasted, (2) ultrasonically cleaned, (3) ultrasonically cleaned followed by silane treatment, (4) rebonded without further treatment. Of the two remaining groups, one was sandblasted, while the brackets in the other were roughened with a greenstone. The brackets were rebonded to the premolar teeth after the enamel surfaces had been re-prepared, and their bond strengths measured.The results indicated that sandblasting was the most effective in removing composite without a significant change in bond strength compared with new attachments. Silane application did not improve the bond strength values of flamed and ultrasonically cleaned brackets. Attachments that had only been flamed had the lowest bond strength, followed by those that had been roughened with a greenstone.

PMID: 15947221 [PubMed - indexed for MEDLINE]

An innovative adhesive procedure for connecting transpalatal arches with palatal implants.

Eur J Orthod. 2005 Jun;27(3):226-30

Authors: Crismani AG, Bernhart T, Bantleon HP, Kucher G

The aim of this presentation is to describe an innovative adhesive procedure for connecting palatal implants with transpalatal arches (TPAs). The steps required for completing the procedure, the costs involved and the requisite time were reviewed and compared with those of two alternative procedures reported in the literature. To establish the stability and reliability of the procedure in vitro, tensile stress tests were performed. The results were evaluated in view of a potential loss of anchorage and compared with reported data.The innovative adhesive procedure ensured a stable and precise connection between TPAs and palatal implants during a single visit in a chair-side time of 42 minutes. The costs incurred were euro 12.33. The composite-connected component parts resisted breakage up to a mean force of 3323.16 cN. Absolute stability of the TPA-palatal implant connection in terms of maximal anchorage was limited to a mean force of 408.05 cN at a wire strength of 0.036 inches.

PMID: 15947220 [PubMed - indexed for MEDLINE]

Influence of autoclave sterilization on the surface parameters and mechanical properties of six orthodontic wires.

Eur J Orthod. 2005 Feb;27(1):72-81

Authors: Pernier C, Grosgogeat B, Ponsonnet L, Benay G, Lissac M

Orthodontic wires are frequently packaged in individual sealed bags in order to avoid cross-contamination. The instructions on the wrapper generally advise autoclave sterilization of the package and its contents if additional protection is desired. However, sterilization can modify the surface parameters and the mechanical properties of many types of material.The aim of this research was to determine the influence of one of the most widely used sterilization processes, autoclaving (18 minutes at 134 degrees C, as recommended by the French Ministry of Health), on the surface parameters and mechanical properties of six wires currently used in orthodontics (one stainless steel alloy: Tru-Chrome RMO; two nickel-titanium shape memory alloys: Neo Sentalloy and Neo Sentalloy with Ionguard GAC; and three titanium-molybdenum alloys: TMA(R) and Low Friction TMA Ormco and Resolve GAC).The alloys were analysed on receipt and after sterilization, using surface structure observation techniques, including optical, scanning electron and atomic force microscopy and profilometry. The mechanical properties were assessed by three-point bending tests.The results showed that autoclave sterilization had no adverse effects on the surface parameters or on the selected mechanical properties. This supports the possibility for practitioners to systematically sterilize wires before placing them in the oral environment.

PMID: 15743866 [PubMed - indexed for MEDLINE]

The effectiveness of three instrumentation techniques on the elimination of Enterococcus faecalis from a root canal: an in vitro study.

J Contemp Dent Pract. 2005 Feb 15;6(1):94-106

Authors: Colak M, Evcil S, Bayindir YZ, Yigit N

The in vitro reduction of a bacterial population in a root canal by mechanical instrumentation using three techniques was evaluated. Root canals inoculated with a Enterococcus faecalis (E. faecalis) suspension were instrumented using hand Hedstroem files, Giromatic files, and Hero 642 rotary instruments. Irrigation was performed using sterile saline solution. Root canals were sampled before and after instrumentation. After serial dilutions, samples were plated onto Mitis-Salivarius agar and the colony forming units grown were counted. All instruments tested were able to significantly reduce the number of bacterial cells in the root canal, however, the results of this study indicated that Hedstroem files, Giromatic, and Hero 642 techniques were not significantly different in their ability to reduce intracanal bacteria.

PMID: 15719081 [PubMed - indexed for MEDLINE]

The effect of multiple uses of disposable diamond burs on restoration leakage.

J Am Dent Assoc. 2005 Jan;136(1):53-7; quiz 90

Authors: von Fraunhofer JA, Smith TA, Marshall KR

BACKGROUND: The authors tested the clinical longevity of disposable diamond burs. They cut a series of five preparations and assessed the leakage after restoring the tooth. METHODS: The authors prepared 10 teeth for Class V restorations, and used a new disposable diamond bur for each tooth. The burs were used to cut preparations in extra teeth before being used to prepare a second series of 10 teeth (third use). The authors then cut preparations in extra teeth before preparing a third set of 10 teeth (fifth use). They removed existing restorations in a second group of 30 teeth and extended the preparations using the same regimen of one, three and five bur uses. All preparations were etched and conditioned, and the teeth were restored with resin-based composite. Using a 20-volt direct-current power source and a stainless-steel counter electrode, the authors measured the leakage electrochemically in 1.0 percent sodium chloride for 30 days. RESULTS: Freshly prepared and restored teeth leaked less than reprepared teeth. Leakage was similar for the first and third uses of the bur, but was far greater for the fifth use (P < .01). The previously restored teeth that were cut with the first- and third-use burs behaved the same, but the third-use bur caused more leakage than the fifth-use bur (P < .01). CONCLUSIONS: Reuse of disposable burs can affect leakage behavior. With new preparations, use of a disposable bur to cut more than three preparations increased leakage. For teeth that were reprepared and restored, greater leakage occurred than it did with new preparations, although repeated use of a bur may reduce leakage. CLINICAL IMPLICATIONS: Disposable diamond burs may cut preparations in up to three teeth before adversely affecting leakage behavior. Restoration removal and repreparation of teeth results in greater leakage than that with freshly prepared teeth.

PMID: 15693496 [PubMed - indexed for MEDLINE]

Factors affecting friction in the pre-adjusted appliance.

Eur J Orthod. 2004 Dec;26(6):579-83

Authors: Moore MM, Harrington E, Rock WP

A jig was constructed to measure the frictional forces created by various tip and torque values in association with two types of straightwire bracket moving along tainless steel (SS) archwires. Forces were measured during translation of the bracket using an Instron machine. Steel and cobalt chromium brackets were tested in association with 0.019 x 0.025 and 0.021 x 0.025 inch steel archwires at tips from 0 to 3 degrees and torque values in 2 degree increments from 0 to 6 degrees.The mean values for static (2.2 N) and kinetic (2.1 N) friction were very similar (P = 0.71), as were the overall friction values for stainless steel (2.1 N) and chromium cobalt (2.2 N) brackets of similar dimensions (P = 0.44). Use of 0.021 x 0.025 inch wire produced three times as much friction as 0.019 x 0.025 inch wire, 3.0 N against 1.2 N (P < 0.01). Increased tip and torque were associated with highly significant increases in friction (P < 0.01). Every degree of tip produced approximately twice as much friction as comparable torque. The main conclusion of the study was that space closure should be completed on a 0.019 x 0.025 inch archwire before a 0.021 x 0.025 inch wire is used to complete tooth alignment.

PMID: 15650066 [PubMed - indexed for MEDLINE]

Six and 12 months' evaluation of a self-etching primer versus two-stage etch and prime for orthodontic bonding: a randomized clinical trial.

Eur J Orthod. 2004 Dec;26(6):565-71

Authors: Aljubouri YD, Millett DT, Gilmour WH

The aim of the study was to compare the mean clinical chair-side time required for bracket bonding and the mean bond failure rate at 6 and 12 months of stainless steel brackets with a micro-etched base bonded with a light-cured composite using a self-etching primer (SEP) or a two-stage etch and prime system.Fifty-one subjects who required upper and/or lower pre-adjusted edgewise fixed appliances were recruited in a single centre randomized clinical trial. The trial was a single-blind design, involving a within-patient comparison of the two bonding systems with each patient randomly allocated the two bonding systems for each side of the mouth (all teeth except molars). The two bonding techniques used were standardized throughout the trial and all bracket bonding was performed by a single operator. Bonding time was recorded using a digital timer. The bond failure rate of a strictly paired sample was recorded at 6 and 12 months for each patient.The mean bracket bonding time per patient with the SEP was significantly less than that with the two-stage bonding system (mean difference 24.9 seconds; 95 per cent confidence interval 22.1-27.7 seconds; paired t-test P < 0.001). The overall bond failure rates at 6 and 12 months with the SEP were 0.8 and 1.6 per cent, respectively, and for the two-stage etch and prime 1.1 and 3.1 per cent, respectively. At 6 months, the mean bond failure rate per patient with the SEP was 0.81 per cent and with the two-stage bonding system 0.96 per cent (P = 0.87; Wilcoxon signed rank test). At 12 months, the mean bond failure rate with the SEP per patient was 1.54 per cent and with the two-stage bonding system 2.78 per cent (P = 0.33; Wilcoxon signed rank test).The mean bracket bonding time with the SEP per patient was significantly shorter than that of the two-stage bonding system (P < 0.001). The difference between the overall bond failure rate and the mean bond failure rate per patient for the two bonding systems was not statistically nor clinically significant at 6 and 12 months (P = 1.00 and P = 0.125, respectively; McNemar's test).

PMID: 15650064 [PubMed - indexed for MEDLINE]

An ex vivo evaluation of resin-modified glass polyalkenoates and polyacid-modified composite resins as orthodontic band cements.

J Orthod. 2004 Dec;31(4):323-8; discussion 301-2

Authors: Knox J, Chye KY, Durning P

OBJECTIVES: The objective of this ex vivo study was to assess the use of resin-modified glass polyalkenoates and polyacid-modified composite resins, as orthodontic band cements. MATERIALS AND METHOD: Plain stainless steel bands were cemented to 350 human extracted third molar teeth using 1 of 7 different cements. Following complete cement cure, half of each sample group was exposed to mechanical stress in a ball mill. Stressed and unstressed samples were tested in tension and the stress at which initial cement failure recorded. The mode of failure was recorded using an adhesive remnant evaluation. RESULTS: The mean band retention stresses offered by the cements studied ranged from 0.96 to 1.56 MPa. Fuji Ortho provided the highest mean band retention stress in "stressed" (1.56 MPa) and "unstressed" (1.45 MPa) states. Exposure to mechanical stress did not appear to significantly influence band retention or mode of cement failure for most cements. Fuji Ortho cement recorded the highest Weibull modulus for all cements tested. Virtually all samples failed at either the cement/enamel or cement band interface. CONCLUSIONS: Significant differences in band displacement stress values and mode of failure were demonstrated between the cements studied. However, generic comparisons were difficult to make.

PMID: 15608348 [PubMed - indexed for MEDLINE]

The effectiveness of laceback ligatures: a randomized controlled clinical trial.

J Orthod. 2004 Dec;31(4):303-11; discussion 300

Authors: Irvine R, Power S, McDonald F

OBJECTIVE: To evaluate the effects of laceback ligatures on the anteroposterior and vertical position of lower incisors and the mesial position of the lower first molars. DESIGN: Randomized controlled trial. SETTINGS: Patients under treatment in the Department of Orthodontics, Royal Bournemouth Hospital, Dorset, during a 6 month period from November 1999 to March 2000. SUBJECTS: Sixty-two adolescents (mean 13.7 years, range 11.2-16.8 years) with similar malocclusions, requiring extraction of all first premolars, were randomly assigned to experimental (laceback: 30; 12 male, 18 female) and control (non-laceback: 32; 14 male, 18 female) groups. INTERVENTIONS: Treatment using upper and lower fixed appliances following extraction of four premolars. One group had lacebacks placed, whilst the control group had no lacebacks. MAIN OUTCOME MEASURES: The participants were examined clinically and radiographically, and lateral cephalograms with radio-opaque tooth markers and lower study casts records were taken when lower fixed appliances were placed (T1) and following sufficient leveling with a 0.018 inch stainless steel round wire (T2). Linear measurements were recorded following digitization of the lateral cephalograms and using a vernier caliper on the study casts. A Student t-test was used to examine differences between the two groups following assessment for normality. RESULTS: In both groups the lower incisors retroclined during T1-T2; (Mean+/-SD: Experimental -0.53+/-1.9 mm, Control -0.44+/-1.29 mm). There was no statistical significance between the two groups (p = 0.84). The lower incisors extruded in both groups; 0.47+/-0.98 mm in the experimental group and 0.44+/-0.87 mm in the control group. There was no statistical difference between the groups (p = 0.9). The lower first molars showed 0.83 mm greater mesial movement in the experimental group, which was statistically significant (p < 0.05). Labial segment crowding decreased in both groups (experimental -3+/-1.6 mm, control -2.67+/-2.28 mm), the difference between the groups being non-significant (p = 0.51). Arch length decreased in both groups (experimental -2.08+/-2.82 mm , control -2.9+/-3.06 mm), but the difference between them was not significant (p = 0.28) CONCLUSIONS: In first premolar extraction cases, the lower labial segment does not procline during the leveling stage with the pre-adjusted edgewise appliance and the use of laceback ligatures conveys no difference in the anteroposterior or vertical position of the lower labial segment. Furthermore, the use of laceback ligatures creates a statistically and clinically significant increase in the loss of posterior anchorage.

PMID: 15608345 [PubMed - indexed for MEDLINE]

Nickel and cobalt hypersensitivity reaction before and after orthodontic therapy in children.

J Contemp Dent Pract. 2004 Nov 15;5(4):79-90

Authors: Saglam AM, Baysal V, Ceylan AM

Nickel and cobalt are major components of alloys used in orthodontics. The objectives of this cross-sectional study was to determine the prevalence of a nickel hypersensitivity reaction before and after orthodontic treatment with conventional stainless steel brackets and wires. The total sample consisted of 82 patients (55 females, and 27 males) from the Orthodontic Department at the Faculty of Dentistry, S&#xFC;leyman Demirel University. A patch test and a questionnaire were used to evaluate hypersensitivity to these metals. The statistical analysis was carried out using Fisher's exact X(2) (2 x 2) test. The prevalence of nickel allergy was found to be higher in females than males (14.55% in females, 0% in males), and the prevalence of cobalt allergy was found to be 9.76% (7.27% in females, 14.81% in males). Orthodontic treatment with conventional stainless steel alloys does not appear to have an allergenic effect on the gingival and oral health of the patient. A family history of an allergy to these metals or the use of metallic objects in contact with the skin do not characterize nickel and cobalt hypersensitivity. This suggests orthodontic therapy with conventional stainless steel appliances does not initiate or aggravate a nickel hypersensitivity reaction. There was no association between the before treatment and after treatment to a nickel and cobalt hypersensitivity reaction.

PMID: 15558093 [PubMed - indexed for MEDLINE]

A 12 month clinical study of bond failures of recycled versus new stainless steel orthodontic brackets.

Eur J Orthod. 2004 Aug;26(4):449-54

Authors: Cacciafesta V, Sfondrini MF, Melsen B, Scribante A

The purpose of this prospective longitudinal randomized study was to compare the clinical performance of recycled brackets with that of new stainless steel brackets (Orthos). Twenty patients treated with fixed appliances were included in the investigation. Using a 'split-mouth' design, the dentition of each patient was divided into four quadrants. In 11 randomly selected patients, the maxillary left and mandibular right quadrants were bonded with recycled brackets, and the remaining quadrants with new stainless steel brackets. In the other nine patients the quadrants were inverted. Three hundred and ten stainless steel brackets were examined: 156 were recycled and the remaining 154 were new. All the brackets were bonded with a self-cured resin-modified glass ionomer (GC Fuji Ortho). The number, cause, and date of bracket failures were recorded over 12 months. Statistical analysis was performed by means of a paired t-test, Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences were found between: (a) the total bond failure rate of recycled and new stainless steel brackets; (b) the upper and lower arches; (c) the anterior and posterior segments. These findings demonstrate that recycling metallic orthodontic brackets can be of benefit to the profession, both economically and ecologically, as long as the orthodontist is aware of the various aspects of the recycling methods, and that patients are informed about the type of bracket that will be used for their treatment.

PMID: 15366391 [PubMed - indexed for MEDLINE]

Torque capacity of metal and polycarbonate brackets with and without a metal slot.

Eur J Orthod. 2004 Aug;26(4):435-41

Authors: Harzer W, Bourauel C, Gmyrek H

The aim of the present study was to investigate slot deformation and the equivalent torque capacity of polycarbonate brackets with and without a metal slot in comparison with those of a metal bracket. For this purpose, the expansion characteristics and, in a further investigation, the labial crown torque of an upper central incisor, were measured in a simulated intra-oral clinical situation, using the orthodontic measuring and simulation system (OMSS). Three types of bracket with a 0.018 inch slot were tested: polycarbonate Brillant without a metal slot, Elegance with a metal slot and the metal bracket, Mini-Mono. For testing purposes the brackets were torqued with 0.016 x 0.022 inch (0.41 x 0.56 mm) and 0.018 x 0.022 inch (0.46 x 0.56 mm) ideal stainless steel archwires. In the activating experiments, significantly higher torque losses and lower torquing moments were registered with both rectangular archwires with the polycarbonate brackets than with the metal bracket. In the simulation tests, significantly higher torquing moments were registered with the metal bracket than with the polycarbonate brackets. The values for the Elegance bracket were between those of the Mini-Mono and Brillant brackets. The OMSS model approximates the clinical situation, with the torque loss being notably higher than in the in vitro activating experiments. This is due to the adjacent teeth giving the archwire additional play. In addition, the torquing process may twist the archwire, resulting in subsidiary forces. On the basis of the present results, all three brackets can be recommended for torquing. However, in view of the high torque losses, the torques programmed in the straightwire technique must be seen as questionable. Data should be provided by the manufacturer on the bending to be expected in polycarbonate brackets, which has to be offset by additional torque, or the bracket torque should be omitted from the technical specifications.

PMID: 15366389 [PubMed - indexed for MEDLINE]

In vitro cytotoxicity of orthodontic archwires in cortical cell cultures.

Eur J Orthod. 2004 Aug;26(4):421-6

Authors: David A, Lobner D

There have been a number of studies regarding the toxicity of orthodontic archwires, but little is known concerning the mechanism of their toxicity. This investigation used murine cortical cell cultures to examine the in vitro neurotoxicity of commonly used orthodontic metallic archwire alloys. The materials examined included 0.016 inch nickel-titanium (NiTi), copper-nickel-titanium, titanium-molybdenum, Elgiloy, and stainless steel archwire alloys. Standard sized samples of each material were placed on tissue culture inserts suspended above the cell cultures. Neuronal death was determined using the lactate dehydrogenase release assay 24 hours after exposure to the archwires. The results indicated that NiTi, copper-nickel-titanium and titanium-molybdenum alloys were not neurotoxic, while stainless steel and Elgiloy were significantly toxic. Washing the archwires for 7 days in a saline solution did not alter the toxicity. However, the free radical scavenger, trolox, blocked the toxicity of both stainless steel and Elgiloy, indicating that the death was free radical mediated. The caspase inhibitor, Z-VAl-Ala-Asp-fluoromethylketone (zVAD-FMK), blocked the toxicity of stainless steel, but not Elgiloy, suggesting that stainless steel induced apoptosis. Further evidence that stainless steel induced apoptosis was provided by propidium staining which showed nuclear chromatin condensation and fragmentation into discrete spherical or irregular shapes, characteristic of apoptosis. The specific metal responsible for the toxicity was not determined; the metals common to each of the toxic archwires were nickel, iron, and chromium.

PMID: 15366387 [PubMed - indexed for MEDLINE]

Three-dimensional finite element analysis in distal en masse movement of the maxillary dentition with the multiloop edgewise archwire.

Eur J Orthod. 2004 Jun;26(3):339-45

Authors: Chang YI, Shin SJ, Baek SH

The purpose of this study was to compare the effects of a multiloop edgewise archwire (MEAW) on distal en masse movement with a continuous plain ideal archwire (IA). Three-dimensional finite element models (FEM) of the maxillary dentition in which the second permanent molars had been extracted were constructed to include the periodontal membrane, alveolar bone, standard edgewise bracket (0.018 x 0.025 inch), stainless steel IA (0.016 x 0.022 inch), and MEAW (0.016 x 0.022 inch). The stress distribution and displacement of the maxillary dentition were analysed when Class II intermaxillary elastics (300 g/side) and 5 degree tip-back bends were applied to the IA and MEAW for distal en masse movement of the maxillary dentition. Compared with the IA, the MEAW showed that the discrepancy in the amount of tooth displacement was lower and individual tooth movement was more uniform and balanced. There was minimal vertical displacement or rotation of the teeth using the MEAW when compared with the IA. The MEAW seems to have advantages for distal en masse movement of the maxillary dentition.

PMID: 15222721 [PubMed - indexed for MEDLINE]

Evaluation of methods of archwire ligation on frictional resistance.

Eur J Orthod. 2004 Jun;26(3):327-32

Authors: Khambay B, Millett D, McHugh S

The aim of the study was to investigate the effect of elastomeric type and stainless steel (SS) ligation on frictional resistance using a validated method. To assess the validity of the new test system to measure mean frictional forces, SS and TMA wires, each with dimensions of 0.017 x 0.025 and 0.019 x 0.025 inches, were used in combination with a self-ligating Damon II bracket or a conventional preadjusted edgewise premolar SS bracket without ligation. Four types of elastomeric module, purple, grey, Alastik or SuperSlick, and a pre-formed 0.09 inch SS ligature were then assessed as methods of ligation using preadjusted edgewise premolar SS brackets. The specimens were tested on a Nene M3000 testing machine, with a crosshead speed of 5 mm/minute and each test run lasted for 4 minutes. Each bracket/wire combination with each method of ligation was tested 10 times in the presence of human saliva and the mean frictional force was recorded. The mean frictional forces were compared using three-way analysis of variance. The Damon II self-ligating bracket and unligated conventional SS bracket produced negligible mean frictional forces with any of the wires tested. For the 0.017 x 0.025 SS, 0.019 x 0.025 SS or 0.019 x 0.025 inch TMA wires, SS ligatures produced the lowest mean frictional forces. With the 0.017 x 0.025 TMA wire, purple modules produced the lowest mean frictional force. There was no consistent pattern in the mean frictional forces across the various combinations of wire type, size and ligation method. Under the conditions of this experiment, the use of passive self-ligating brackets is the only method of almost eliminating friction.

PMID: 15222719 [PubMed - indexed for MEDLINE]

Evaluation of shear bond strength with different enamel pre-treatments.

Eur J Orthod. 2004 Apr;26(2):179-84

Authors: Abu Alhaija ES, Al-Wahadni AM

The purpose of this study was to investigate the shear bond strengths of two adhesives, Panavia-21 and a composite resin (Transbond XT), with different enamel pre-treatments, acid etching (37 per cent phosphoric acid) and grit blasting (50 microm aluminium oxide particles). The mode of bond failure was also assessed using the modified adhesive remnant index (ARI). Ninety freshly extracted non-carious human premolar teeth were randomly divided into the following groups: (1) Transbond XT, acid-etched enamel surface; (2) Panavia-21, acid-etched enamel surface; (3) Transbond XT, grit-blasted enamel surface; (4) Panavia-21, grit-blasted enamel surface; (5) Transbond XT, acid-etched enamel surface with grit-blasted brackets; (6) Panavia-21, acid-etched enamel surface with grit-blasted brackets. All groups had stainless steel brackets bonded to the buccal surface of each tooth. An Instron universal testing machine was used to determine the shear bond strengths at a crosshead speed of 0.5 mm/second. Statistical analysis was undertaken using analysis of variance and the Tukey test. The mean bond strength values were as follows: group 1, 135.7 +/- 23.0 N; group 2, 181.5 +/- 18.4 N; group 3, 38.4 +/- 27.5 N; group 4, 59.1 +/- 24.1 N; group 5, 106.7 +/- 21.5 N; group 6, 165.3 +/- 21.4 N. Panavia-21 with the acid-etched enamel surface had a significantly higher shear bond strength than the other groups (P < 0.001). This was followed by the composite group with the acid-etched enamel surface. This group differed significantly from the composite and Panavia-21 groups with the grit-blasted tooth surface (P < 0.001) and from the composite and Panavia-21 groups with the acid-etched enamel surface and grit-blasted brackets (P < 0.01). The current findings indicate that Panavia-21 is an excellent adhesive and produces a bond strength that is clinically useful. Enamel surface preparation using grit blasting alone results in a significantly lower bond strength and should not be advocated for clinical use.

PMID: 15130041 [PubMed - indexed for MEDLINE]

Metal ion release from new and recycled stainless steel brackets.

Eur J Orthod. 2004 Apr;26(2):171-7

Authors: Huang TH, Ding SJ, Min Y, Kao CT

As orthodontic appliances can corrode with time in the oral environment, the aim of this study was to compare the release of metal ions from new and recycled brackets immersed in buffers of different pH values over a 48 week period. To simulate commercial recycling, the stainless steel brackets were divided into two groups: new and recycled. The bases of the latter were coated with adhesive and the brackets were heat treated before being immersed in the test solution for 48 weeks. The release of nickel, chromium, iron, copper, cobalt and manganese ions was analysed by atomic absorption spectrophotometry. Differences were compared using one-way analysis of variance. The results showed that recycled brackets released more ions than new brackets (P < 0.05). Brackets immersed in solutions of pH 4 released more ions than those immersed in solutions of pH 7, and the total amount of ions released increased with time over the 48 week period (P < 0.05). This study demonstrates that both new and recycled brackets will corrode in the oral environment. To avoid clinical side-effects, metal brackets should be made more resistant to corrosion, and recycled brackets should not be used.

PMID: 15130040 [PubMed - indexed for MEDLINE]

Dynamic frictional behaviour of orthodontic archwires and brackets.

Eur J Orthod. 2004 Apr;26(2):163-70

Authors: Clocheret K, Willems G, Carels C, Celis JP

The aim of this study was to evaluate the frictional behaviour of 15 different archwires and 16 different brackets using small oscillating displacements when opposed to a standard stainless steel bracket or a standard stainless steel wire. Tests were run according to a pilot study at a frequency of 1 Hz and with a reciprocating tangential displacement of 200 microm, while the wire remained centred in the bracket slot under a load of 2 N. The results indicated a significant difference between the evaluated wires and brackets. The mean coefficient of friction (COF) of the wires varied from 0.16 for Imagination NiTi tooth-coloured wire to 0.69 for the True Chrome Resilient Purple wire, while for the brackets it ranged from 0.39 for Ultratrimm to 0.72 for the Master Series. The fact that in this study, a large number of different commercially available archwires and brackets were evaluated with the same apparatus according to the same protocol, allows a direct comparison of the different archwire and bracket combinations, and can assist in the choice of the optimal bracket-wire combination with regard to friction.

PMID: 15130039 [PubMed - indexed for MEDLINE]

A randomized controlled trial comparing mandibular local anesthesia techniques in children receiving nitrous oxide-oxygen sedation.

Anesth Prog. 2004;51(1):19-23

Authors: Naidu S, Loughlin P, Coldwell SE, Noonan CJ, Milgrom P

The aim of this study was to test the hypothesis that dental pain control using infiltration/intrapapillary injection was less effective than inferior alveolar block/long buccal infiltration anesthesia in children. A total of 101 healthy children, aged 5-8 years, who had no contraindication for local anesthetic and who needed a pulpotomy treatment and stainless steel crown placement in a lower primary molar were studied. A 2-group randomized blinded controlled design was employed comparing the 2 local anesthesia techniques using 2% lidocaine, 1:100,000 epinephrine. All children were given 40% nitrous oxide. Children self-reported pain using the Color Analogue Scale. The study was conducted in a private pediatric dental practice in Mount Vernon, Wash. Overall pain levels reported by the children were low, and there were no differences between conditions at any point in the procedure. Pain reports for clamp placement were block/long buccal 2.8 and infiltration/intrapapillary 1.9 (P = .1). Pain reports for drilling were block/long buccal 2.0 and infiltration/intrapapillary 1.8 (P = .7). Nine percent of children required supplementary local anesthetic: 4 of 52 (7.7%) in the block/long buccal group and 5 of 49 (10.2%) in the infiltration/intrapapillary group (P = .07). The hypothesis that block/long buccal would be more effective than infiltration/intrapapillary was not supported. There was no difference in pain control effectiveness between infiltration/intrapapillary injection and inferior alveolar block/long buccal infiltration using 2% lidocaine with 1:100,000 epinephrine when mandibular primary molars received pulpotomy treatment and stainless steel crowns.

PMID: 15106686 [PubMed - indexed for MEDLINE]

A comparative study of the static and kinetic frictional resistance of titanium molybdenum alloy archwires in stainless steel brackets.

Eur J Orthod. 2004 Feb;26(1):105-11

Authors: Cash A, Curtis R, Garrigia-Majo D, McDonald F

This ex vivo study compared the static and kinetic frictional resistance of eight different archwires tested in a single, stainless steel, zero base 0.022 x 0.028 inch (0.56 x 0.711 mm) slot standard edgewise bracket. The archwires evaluated were 0.019 x 0.025 inch (0.483 x 0.636 mm) in dimension, manufactured from the following alloys: beta titanium (TMA), 'low friction' coloured beta titanium (aqua, honeydew, purple and violet), ion-implanted beta titanium, Timolium and a stainless steel control. Prior to friction testing, bracket and archwire dimensions were measured by direct digital imaging via a desktop computer linked to a binocular light microscope. Frictional force was evaluated using an Instron universal testing machine. All experiments were carried out at room temperature, with no ligation, in the dry state with 20 degrees of added torque. The results demonstrated that static and kinetic friction were statistically significant (P < 0.001) for all archwire types. Ion-implanted and standard TMA archwires were found to have no significant advantage over stainless steel. The archwire alloys may be ranked as follows: stainless steel produced the lowest frictional resistance followed by honeydew, ion-implanted TMA and Timolium, with aqua, purple and violet producing frictional resistance values as high as standard TMA. It was also found that the percentage difference between the archwire and bracket slot dimensions claimed by the manufacturers and those measured in this experiment produced tolerances ranging from +5.37 to -6.67 per cent.

PMID: 14994890 [PubMed - indexed for MEDLINE]

[A clinical study of twin-wires on anchorage reinforcement]

Shanghai Kou Qiang Yi Xue. 2002 Dec;11(4):307-9

Authors: Shen G, Chen RJ, Ding KM, Dong XJ

OBJECTIVE: This clinical trial was designed to impose a simultaneous placement of large-size stainless steel round wire and small-size NiTi, and to assess its effect on anchorage reinforcement. METHODS: Twin-arch wires were in place for relief of severe crowding. Distalization of canines were well conducted with support of rigid wire, together with a simultaneous repositioning of upper lateral incisors facilitated by resilient wire. The linear distance between APo and the first molar, together with other parameters, was measured for the evaluation of anchorage consolidation. RESULTS: Anchorage molars and anteriors, as well as the integrity of dental arches remained unchanged upon fulfillment of crowding relief, which was justified by statistical analysis. CONCLUSION: Application of Twin-wires leads to a concurrence of efficient crowding relief and sufficient anchorage consolidation.

PMID: 14983364 [PubMed]

General dentists' perceptions of educational and treatment issues affecting access to care for children with special health care needs.

J Dent Educ. 2004 Jan;68(1):23-8

Authors: Casamassimo PS, Seale NS, Ruehs K

This study analyzed a data subset of a national survey of general dentists conducted in 2001 to determine their overall care of children with special health care needs (CSHCN). In the survey, dentists were asked to respond to questions in the following areas: did they provide care for CSHCN (children with cerebral palsy, mental retardation, and those who are medically compromised); what were their perceptions of the training they received in dental school related to CSHCN; what was their interest in additional training for CSHCN; and what factors influenced their willingness to provide care for CSHCN? Only about 10 percent see CSHCN often or very often, and only one in four respondents had hands-on experience with these patients in dental school. Postgraduate education in general practice or advanced general dentistry residency had no effect on willingness to care for CSHCN. Older dentists, those accepting Medicaid for all children, and those practicing in small communities were more likely to see CSHCN. Dentists willing to see CSHCN also were more likely to perform procedures associated with special needs and underserved child populations including pharmacologic management and stainless steel crowns. Dentists with hands-on educational experiences in dental schools with CSHCN were less likely to consider such factors as level of disability and patient behavior as obstacles to care and were more likely to desire additional education in care of CSHCN.

PMID: 14761169 [PubMed - indexed for MEDLINE]

Finite elements study of the Flexi Post and Flexi Flange post systems in a maxillary central incisor.

Pesqui Odontol Bras. 2003 Apr-Jun;17(2):132-6

Authors: Lewgoy HR, Youssef MN, Matson MR, Bocangel JA, Netto CA, Amore R

The use of post and core systems has become an excellent alternative for restoring endodontically treated teeth. The aim of this study was to evaluate the von Mises, maximal compressive and tensile stresses distribution using the Finite Element Method (FEM) on human teeth restored with different post and core systems. The analysis was made on endodontically treated maxillary central incisors. The post systems used in this investigation were the stainless steel or titanium Flexi Post/Flexi Flange. Composite resin was used as core material and resin cement was the cement material of choice to seat a full porcelain crown. The bi-dimensional mathematical model was created from pictures taken from an intact human maxillary central incisor and prefabricated posts. This image was transferred to a personal computer in the MSC/Nastran 4.5 software. A static and linear analysis treatment was performed when a 45 load of 100 N was applied on the lingual surface of the tooth. Based on the results obtained, it can be concluded that the post design and its material can alter the stress pattern distribution.

PMID: 14569354 [PubMed - indexed for MEDLINE]

A clinical investigation of force delivery systems for orthodontic space closure.

J Orthod. 2003 Sep;30(3):229-36

Authors: Nightingale C, Jones SP

OBJECTIVE: To investigate the force retention, and rates of space closure achieved by elastomeric chain and nickel titanium coil springs. DESIGN: Randomized clinical trial. SETTING: Eastman Dental Hospital, London and Queen Mary's University Hospital, Roehampton, 1998-2000. Subjects, materials and methods: Twenty-two orthodontic patients, wearing the pre-adjusted edgewise appliance undergoing space closure in opposing quadrants, using sliding mechanics on 0.019 x 0.025-inch posted stainless steel archwires. Medium-spaced elastomeric chain [Durachain, OrthoCare (UK) Ltd., Bradford, UK] and 9-mm nickel titanium coil springs [OrthoCare (UK) Ltd.] were placed in opposing quadrants for 15 patients. Elastomeric chain only was used in a further seven patients. The initial forces on placement and residual forces at the subsequent visit were measured with a dial push-pull gauge [Orthocare (UK) Ltd]. Study models of eight patients were taken before and after space closure, from which measurements were made to establish mean space closure. MAIN OUTCOME MEASURES: The forces were measured in grammes and space closure in millimetres. RESULTS: Fifty-nine per cent (31/53) of the elastomeric sample maintained at least 50 per cent of the initial force over a time period of 1-15 weeks. No sample lost all its force, and the mean loss was 47 per cent (range: 0-76 per cent). Nickel titanium coil springs lost force rapidly over 6 weeks, following that force levels plateaued. Forty-six per cent (12/26) maintained at least 50 per cent of their initial force over a time period of 1-22 weeks, and mean force loss was 48 per cent (range: 12-68 per cent). The rate of mean weekly space closure for elastomeric chain was 0.21 mm and for nickel titanium coil springs 0.26 mm. There was no relationship between the initial force applied and rate of space closure. None of the sample failed during the study period giving a 100 per cent response rate. CONCLUSIONS: In clinical use, the force retention of elastomeric chain was better than previously concluded. High initial forces resulted in high force decay. Nickel titanium coil springs and elastomeric chain closed spaces at a similar rate.

PMID: 14530421 [PubMed - indexed for MEDLINE]

Laboratory evaluation of a self-etching primer for orthodontic bonding.

Eur J Orthod. 2003 Aug;25(4):411-5

Authors: Aljubouri YD, Millett DT, Gilmour WH

The aim of the present study was to compare the mean bonding time, mean shear bond strength and mean survival time of stainless steel brackets with a micro-etched base bonded with a light-cure composite using a self-etching primer (SEP) or a conventional two-stage etch and prime system. Brackets were bonded to 30 premolars with each bonding system. The bonding time was recorded for each specimen using a stopwatch. After storage in a humidor at 37 degrees C for 24 hours, the shear debonding force was measured at a crosshead speed of 0.5 mm/minute. Another 10 premolars were bonded with each bonding system and used to assess survival time following the application of mechanical stress in a ball mill for 100 hours. The mean bonding time of the SEP group (111.5 seconds) was significantly less than that of the two-stage bonding group (170.5 seconds) [mean difference 59 seconds; 95 per cent confidence interval (CI) 51.8-66.2 seconds, two sample t-test P < 0.001]. The mean shear bond strength of the SEP group (2.88 MPa) was significantly less than that of the two-stage bonding group (3.71 MPa) (mean difference 0.83 MPa; 95 per cent CI 0.23-1.42 MPa; two sample t-test P = 0.008). For the survival study, only one of the two-stage bonding group failed within 1 hour in the ball mill. The SEP significantly reduced bracket bonding time. The mean shear bond strength of the brackets bonded with the SEP was significantly less than those bonded with a conventional two-stage etch and prime system. There was no difference in survival time of brackets bonded by each bonding system.

PMID: 12938848 [PubMed - indexed for MEDLINE]

Constant versus dissipating forces in orthodontics: the effect on initial tooth movement and root resorption.

Eur J Orthod. 2003 Aug;25(4):335-42

Authors: Weiland F

The aim of this clinical and confocal laser scanning microscopic study was to compare the effects of two frequently used archwires on tooth movement and root resorption. A total of 84 premolars in 27 individuals (10 boys, 17 girls, with a mean age of 12.5 years) was moved buccally with an experimental fixed orthodontic appliance. In a split mouth experimental design the premolar on one side was activated with a stainless steel wire with a buccal offset of 1 mm, which was reactivated every four weeks and the contralateral premolar was moved with a superelastic wire with a force plateau of 0.8-1 N. This wire had an initial activation of 4.5 mm and was not reactivated during the 12-week experimental period. At the end of the experimental period the teeth were extracted. Six premolars were used as control teeth and were extracted before the experiment started. Tooth displacement was studied three-dimensionally on dental casts with a co-ordinate measuring machine. The depth, perimeter, area, and volume of the resorption lacunae was measured using three-dimensional digital images made with a confocal laser scanning microscope (CLSM). On these images the resorbed portions of the root surface were 'reconstructed' mathematically. The results show that the teeth activated with the superelastic wire moved significantly more than the teeth with the steel wire during the experimental period. The depth of the resorption lacunae did not differ significantly between the groups; however, perimeter, area, and volume of the resorption lacunae on the teeth of the 'superelastic group' were 140 per cent greater than on the teeth of the 'steel group'. It may be concluded that a greater amount of tooth movement occurred with superelastic wires, offering a force level of 0.8-1 N compared with stainless steel wires, with initially higher but rapidly declining forces in an experimental set up for a period of 12 weeks. The amount of root resorption was significantly larger in the superelastic group.

PMID: 12938838 [PubMed - indexed for MEDLINE]

Nickel allergy and orthodontics.

J Orthod. 2003 Jun;30(2):171-4

Authors: Rahilly G, Price N

Nickel is the most common metal to cause contact dermatitis in orthodontics. Nickel-containing metal alloys, such as nickel-titanium and stainless steel, are widely used in orthodontic appliances. Nickel-titanium alloys may have nickel content in excess of 50 per cent and can thus potentially release enough nickel in the oral environment to elicit manifestations of an allergic reaction. Stainless steel has a lower nickel content (8 per cent). However, because the nickel is bound in a crystal lattice it is not available to react. Stainless steel orthodontic components are therefore very unlikely to cause nickel hypersensitivity. This article discusses the diagnosis of nickel allergy in orthodontics and describes alternative products that are nickel free or have a very low nickel content, which would be appropriate to use in patients diagnosed with a nickel allergy.

PMID: 12835436 [PubMed - indexed for MEDLINE]

In vivo evaluation of two new moisture-resistant orthodontic adhesive systems: a comparative clinical trial.

J Orthod. 2003 Jun;30(2):139-47; discussion 127-8

Authors: Mavropoulos A, Karamouzos A, Kolokithas G, Athanasiou AE

OBJECTIVE: To evaluate and compare the clinical performance of two new moisture-resistant orthodontic adhesive systems: a chemically-cured composite resin (Unite, 3M Unitek, Monrovia, California, USA) in conjunction with a special moisture-resistant primer (Transbond MIP, 3M Unitek, Monrovia, California, USA); and a fluoride-releasing light-cured compomer (Assure, Reliance Orthodontic Products, Inc., Itasca, Illinois, USA). DESIGN: Randomized controlled clinical trial using the 'split-mouth' technique. SETTING: Department of Orthodontics, Aristotle University of Thessaloniki. Subjects (Materials) and Methods: Twenty-five consecutively started patients (13 females and 12 males) requiring fixed appliance orthodontic treatment. INTERVENTIONS: Four-hundred-and-thirty-six stainless steel brackets bonded to all teeth except molars using two different moisture-resistant orthodontic adhesive systems. MAIN OUTCOME MEASURES: Bond failure rates during a period of 9 months were estimated for each adhesive system and the corresponding bracket survival curves were plotted using the Kaplan- Meier product-limit estimate. Bracket survival distributions with respect to adhesive material, tooth location, patient's gender and operator, were then compared by means of a log-rank test. Bond failure interface was determined using the Adhesive Remnant Index. RESULTS: Assure recorded a higher bond failure rate (13.8 per cent) than Unite & MIP (7.3 per cent). The corresponding bracket survival curves were found to be significantly different (P < 0.05). Premolars exhibited higher bond failures than incisors and canines (P < 0.001), while half (49.8 per cent) of the total bond failures occurred during the first 2 months of treatment. The predominant mode of failure was within the bonding material. CONCLUSION: The new moisture-resistant adhesive systems under study were found to be clinically efficient, though Assure exhibited a significantly higher bond failure rate than Unite and Transbond MIP. The higher frequency of adhesive failures observed with Assure might indicate a possible weak point at the adhesive-bracket interface.

PMID: 12835430 [PubMed - indexed for MEDLINE]

Photo-elastic stress analysis of initial alignment archwires.

Eur J Orthod. 2003 Apr;25(2):117-25

Authors: Badran SA, Orr JF, Stevenson M, Burden DJ

Photo-elastic models replicating a lower arch with a moderate degree of lower incisor crowding and a palatally displaced maxillary canine were used to evaluate the stresses transmitted to the roots of the teeth by initial alignment archwires. Six initial alignment archwires were compared, two multi-strand stainless steel wires, two non-super-elastic (stabilized martensitic form) nickel titanium wires, and two stress-induced super-elastic (austenitic active) nickel titanium wires. Three specimens of each archwire type were tested. Analysis of the photo-elastic fringe patterns, in the medium supporting the teeth, revealed that the non-super-elastic nickel titanium archwires produced the highest shear stresses (P = 0.001). However, the shear stresses generated by the super-elastic alignment archwires and the multi-strand stainless steel archwires were very similar (P = 1.00). These results show that even in situations where large deflections of initial alignment archwires are required, super-elastic archwires do not appear to have any marked advantage over multi-strand stainless steel alignment archwires in terms of the stresses transferred to the roots of the teeth.

PMID: 12737209 [PubMed - indexed for MEDLINE]

Orthodontic treatment for jaw deformities in cleft lip and palate patients with the combined use of an external-expansion arch and a facial mask.

Bull Tokyo Dent Coll. 2002 Nov;43(4):223-9

Authors: Sakamoto T, Sakamoto S, Harazaki M, Isshiki Y, Yamaguchi H

Patients with cleft lip and palate can suffer from contraction of the maxillary arch and anterior cross-bite accompanied by skeletal growth retardation. We use an appliance called an external-expansion arch and induce maxillary protraction using a facial mask in order to correct the anterior cross-bite and maxillary retrusion. In this paper, the method of application of these appliances and the effects of this therapy are reported here. The external-expansion arch consists of a labial wire, bands and a sectional arch. The 0.045-inch stainless steel wire extends along the maxillary dental arch. Hooks are soldered immediately distal to the lateral incisor and the distal leg of the vertical loop. The brackets are bonded to the maxillary anterior teeth, and a 0.016 x 0.016 inch sectional arch is set. The external-expansion arch is inserted into the headgear tube and ligated with the sectional arch using elastic thread. The maxillary bone is pulled by use of the facial mask and the elastic band. For traction, the force is about 300 g on each side, applied parallel to the occlusal plane or slightly downward. The duration of use is 8 to 12 hours per day. The external-expansion arch has several advantages: it can be applied from the early period of Hellman's dental age IIIA or IIC to improve anterior cross-bite. As it is easy to expand the anterior teeth and move individual teeth to the labial and buccal sides, establishment of a dental arch from severe collapse is not difficult. When an expanding device such as the Quad-helix is incorporated, lateral expansion becomes easier. Furthermore, it is easy to control the teeth vertically, and patient compliance is not necessary. Hence, this method is effective as a phase 1 treatment for orthodontic patients with cleft lip and palate characterized by maxillary retardation.

PMID: 12687727 [PubMed - indexed for MEDLINE]

Surface roughness of composite resins after finishing and polishing.

Braz Dent J. 2003;14(1):37-41

Authors: Nagem Filho H, D'Azevedo MT, Nagem HD, Marsola FP

This study evaluated the effect of surface finishing methods on the average surface roughness of resin composites. Seven composites and two polishing systems were used. One hundred and twenty-six conical specimens of each material were prepared in stainless steel molds against a polyester strip. Forty-two of them remained intact and were used as controls. Each half of the remaining samples was polished with either diamond burs or diamond burs + aluminum oxide discs. The results showed no statistical difference in average surface roughness (Ra, microm) between the polyester strip and aluminum oxide discs (p > 0.05). However, finishing with diamond burs showed a statistically higher average roughness for all composites (p < 0.05). Statistical differences were detected among materials (p < 0.05) in the use of diamond burs.

PMID: 12656463 [PubMed - indexed for MEDLINE]

Salivary metal levels of orthodontic patients: a novel methodological and analytical approach.

Eur J Orthod. 2003 Feb;25(1):103-6

Authors: Eliades T, Trapalis C, Eliades G, Katsavrias E

The purpose of this study was to qualitatively and quantitatively assess the nickel, chromium, and ferrous levels in a population of 17 orthodontic patients undergoing treatment, compared with seven untreated individuals, employing a novel methodological approach and a new analytical technique. Salivary samples obtained from patients before and after rinsing with double distilled water were processed for Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) for simultaneous estimation of the concentration of the metallic elements. No statistically significant difference was detected between control and patient groups with respect to salivary metal content, regardless of element. The range of salivary metal levels found did not exceed those of daily intake through food and air. The lack of a continuous monitoring scheme for salivary metal concentrations in real time may impose substantial obstacles to defining the release rate of metals in vivo. The results of this study emphasize the necessity of incorporating the dimension of time in assessing the release potential of orthodontic alloys.

PMID: 12608730 [PubMed - indexed for MEDLINE]

Shear bond strength of a new dental adhesive used to bond brackets to unetched enamel.

Eur J Orthod. 2002 Oct;24(5):519-23

Authors: Harari D, Gillis I, Redlich M

The aims of the present study were to measure the shear bond strength of a new multipurpose dental adhesive, IntegraCem, for direct bonding of stainless steel and ceramic brackets to unetched enamel, and to determine the mode of bond failure. Both stainless steel and ceramic brackets (GAC) were bonded with IntegraCem to unetched extracted human premolars. After bonding, the teeth were either stored in a water bath at 37 degrees C for 3 days or passed 2500 thermocycles from 6 to 60 degrees C. Debonding was then performed with a shearing force using an Instron universal testing machine. The force was recorded at bond failure. The results showed that the shear bond strength achieved was between 6.7 and 10.8 megapascals (MPa). Bond failure occurred at the enamel-adhesive interface, enabling more efficient enamel clean up. The shear bond strengths measured suggest that IntegraCem adhesive may be effectively used in orthodontic treatment.

PMID: 12407947 [PubMed - indexed for MEDLINE]

Evaluation of compressed air used in the dental operatory.

J Am Dent Assoc. 2002 Jul;133(7):837-41

Authors: Hubar JS, Pelon W, Gardiner DM

BACKGROUND: The authors report the findings obtained when they quantitatively examined compressed air samples from air-water syringes located in different dental operatories at the Louisiana State University School of Dentistry fo r the presence of microbial contaminants. METHODS: Streams of air of 30 seconds' duration from air-water syringes were forced through sterile modified stainless steel membrane filter holders (Millipore, Millipore Corp., Bedford, Mass.), each containing a membrane filter (average pore diameter = 0.45 micrometers). Each filter was aseptically removed, placed onto the surface of a Petri dish containing sheep blood agar and incubated under increased carbon dioxide tension at 37 C for 48 hours. The authors performed a count of the resultant microbial colonies, after which they microscopically examined the gram-stained organisms. RESULTS: Bacteria were detected in 24 percent of the samples. The number of colonies observed on the filters varied among the dental units. The air from only one of the dental units sampled repeatedly was found to be free of bacterial contaminants. This contrasted with other units for which one or more samples were found to be positive for microorganisms. The majority of colonies observed were pigmented. Microscopic examination of organisms from representative colonies revealed that most were either gram-positive cocci or gram-negative diplococci and tetrads. The results of the one-sample t test were found to be significant (t = 5.6, df = 98, P = .0001). The 95 percent confidence interval was 0.15 to 0.32. CONCLUSION: The results suggest that, at least statistically, a percentage of air lines will have bacteria present.

PMID: 12148676 [PubMed - indexed for MEDLINE]